So, our backyard is looking terrible with cement pieces just falling apart, im just looking to get it all removed and plant some grass in there, any help on how i should do it ? With what tools i would do it better with ? Some pics down here.

You'll need a heavy sledge hammer, maybe a pick-ax and shovel (preferably with a straight bottom similar to this one
http://www.lowes.com/pd_334318-302-1592800_4294612716__?productId=3415998&Ns=p_product_qty_sales_dollar|1&pl=1&currentURL=%3FNs%3Dp_product_qty_sales_dollar%7C1&facetInfo=

Then - your soil there looks terrible for growing anything - it will be highly compacted under that concrete rubble. I would cover the whole area with a thick layer of fresh wood chips for a year - this will promote the growth of beneficial fungi at the junction between the soil and the wood chips. After a year or so of wood chips, the area should be much more friable and then can be planted with whatever you like.

What other options do i have to floor it without planting grass ? I was thinking about gravil and a fence like these, what do you guys think ?

the fencing is going to be higher obviously

i moved this to our gardening section
if your dead set on grass Amy had great advice but make sure its natural wood chips and not colored ones. cider is great.
the only thing with the gravel is you will be throwing a lot of it away with poop. is the fencing to keep the dog in? as they will climb that, at any height. I would just try the wood chips.

It looks quite heavily shaded?? If so then I would forget growing grass. Gravel and bark will be a real pain in the butt as well. There are some wonderful fake grasses available these days. They have drainage holes and you will be able to pick up the poop and hose down easily. You will still need to remove all of the concrete and apply a layer of sand to level out.

There are many shaded ground cover plants that will grow in shade and or sun, the thing you will need to be mindful of, is that grass or most grounds covers will be badly burnt by urine.

Good luck with it, its a nice area and a great blank canvass to work with.

I hate grass, I would just put in some good soil and add some nice plants that fit. I don't like to mow. I wouldn't use that fence either, they will just climb it. Privacy fences work.